In the composites industry, the standard practice for resin infusion may include preparing the fiber pre-form on a tooling surface and vacuum bagging or preparing the fiber pre-form in a closed mold. To infuse the pre-form, a resin container may be connected to the tooling via a conduit. Once plumbed, air may be evacuated from the pre-form and the conduit and a resin pumped from the resin container, through the conduit and into the space which was formerly occupied by the evacuated air. The resin may be pumped through the conduit by applying air pressure to the resin in the resin container or by operation of a mechanical pump.
For high-temperature structural thermosetting resin systems, the resin container may be heated to attain the correct viscosity of the resin before infusion begins. Once the fiber pre-form is infused with the resin, the infused pre-form and fiber pre-form may be heated to a cure temperature. The resin within the resin container may not be cured with the tool as the volume-to-surface area may result in an exothermic reaction for most thermo-set plastic resin systems used in resin infusion. This may necessitate a process in which the pre-form being infused is placed in an oven and the conduit for the resin infusion is passed from the resin container through the oven wall. The resin and conduit outside the oven may be heated using separate heating units.
The conventional resin-infusion process may be attended by several drawbacks. For example, preparing conduit connections and plumbing may be time-consuming and laborious. Conduits which contain cured resin may not be re-usable and this may contribute cost to the process. Conduit connections in which resin has cured may require cleaning and refurbishment. Significant waste resin may remain within the conduit and the sump of the resin container. Removal of uncured resin from the resin container and disposal of the resin may be difficult and may represent a significant health, safety and environmental risk. Separate heating sources may be required for the resin and the tool. If a mechanical pump is used to infuse the fiber pre-form, the pump may require cleaning and flushing of all resin between jobs or production runs. Plumbing may need separate heating to keep the resin at the correct viscosity as it flows through the conduit.
One solution to some of the drawbacks of the conventional resin infusion process includes increasing the viscosity of the resin until it is a solid at room temperature and placing the solid resin under the vacuum bagging. As the pre-form is heated, the resin melts and the pressure on the vacuum bagging pushes the liquefied resin into the pre-form. However, there may be no control over when or how the resin flows as the pre-form is infused. Another solution includes using a pre-preg material in which the resin is already impregnated into the fabric. The pre-preg material is cured under high pressure to obtain full compaction. However, this process may increase the cost of the composite material product and result in movement/compaction of the pre-form from the initial laid up state. This may render difficult manufacture of complex parts to tight tolerances. Moreover, the system may not be applicable to use in closed molding processes such as Resin Transfer Molding. Additionally, the process may require expensive processing equipment and a premium may be paid for raw materials processed to fabricate pre-impregnated fabrics of aerospace quality.
Therefore, a resin containment and injection system and method are needed in which the resin and the fiber pre-form which is to be impregnated with the resin may be placed together on the same tool to simplify the resin infusion process.